[CentOS] strange su behavior

From: Uwe Kiewel <ml at kiewel-online.ch>
> If I am root and want to change the user to a non-root user, the system
> prompts me for a password:
> [root at halifax ~]# useradd test00
> [root at halifax ~]# su - test00
> We trust you have received the usual lecture from the local System
> Administrator. It usually boils down to these three things:
> #1) Respect the privacy of others.
> #2) Think before you type.
> #3) With great power comes great responsibility.
> Password:
> [test00 at halifax ~]$ logout
> [root at halifax ~]# su - test00
> [test00 at halifax ~]$ logout
> [root at halifax ~]#
> At this test procedure I just hit the enter key at the password promt.
> Do you have any idea for this behavoir? I expect to do so from root to
> any account _without_ being prompted for the password.
Do you have any sudo call from your /etc or /etc/skel bashrc or profile...?
JD